1. Field of the Invention
The present invention relates to a method of securing a mobile telecommunication terminal. It also relates to a mobile terminal including means for implementing the method.
2. Description of the Prior Art
A true social phenomenon, the mobile telephone is part of our everyday environment, with hundreds of millions of mobile telephones in use worldwide. These telecommunication terminals generally include a microchip card conventionally referred to as a (U)SIM card.
A (U)SIM card contains information that cannot be modified by the user and which identifies the card and the user, for example by numbers consisting of the identification number (ICCid) of the integrated circuit on the card and the international mobile subscriber identity (IMSI) of the user. The (U)SIM card is handed over by a telecommunication operator when a mobile telephone is acquired. It is inserted into the mobile telephone and activates the latter when the user enters a personal identification number (PIN) via the keypad.
The PIN is stored in a secure manner by the card and is known only to the user. Each time the telephone is switched on, the user is prompted to enter the PIN, unless this function has been disabled.
The (U)SIM card further contains in non-volatile memory a program for communicating with the terminal. The program corresponds to the protocol for communication with mobile telephone terminals conforming to the GSM TS 11—11 and 3GPP (TS 31.101) standards.
The (U)SIM card also contains one or more application programs in a program memory.
The mobile terminal of a user Ao is consequently equipped with a reader for (U)SIM smart cards, which in particular identify the user. The reader enables communication with the (U)SIM card Co of the user. To this end the card reader includes a man-machine interface enabling interaction of the user and the card via the terminal. For the purposes of this dialog, the user has access to a display (screen) and input (keyboard) interface.
The terminal is also equipped with other electronic circuits that there is no need to describe in detail for an understanding of what follows, such as data processing means, program and data storage means, and mean, for communication with the outside world, for example with another electronic device and also with one or more telecommunication networks.
The problem addressed is explained hereinafter.
The growth in the mobile telephone market has given rise to a growing black market in stolen mobile telephones.
A thief stealing the telephone of another person can use it if it is active until the battery runs out. After that, he cannot use it without knowing the owner's PIN (if the function is activated, which is the default option). However, it is entirely possible for the thief to install another smart card (of the (U)SIM or other type) and to use the stolen mobile telephone with the new smart card.
Thus a recent technology telephone may be stolen to replace an old telephone. There is therefore a trade in stolen telephones, since persons acquiring them can use them, for example by inserting a prepaid calling card, or recover the (U)SIM card from an old design of telephone and install it in the purchased/stolen new design.
This market is viable in that it is possible to use a telephone with a (U)SIM card other than that of the original user.
One solution to this problem known to the person skilled in the art is to lock the operation of the mobile telephone to the (U)SIM card with which it was supplied in a purchase pack (telephone and subscription). This SIM Lock mechanism is defined by the ETSI. It protects the operator against the use of a telephone with a subscription taken out with another operator. This solution is managed by the telecommunication operator for a limited time period. Because this is a mature market, consumers purchase recent terminals to use with their existing subscription (SIM). In practical terms, a user whose telephone has been stolen calls his telecommunication operator to report the theft and the operator blocks the use of his (U)SIM card. It can be seen that this solution protects the user against the use of his subscription (although his PIN would have to be found out, if the function is active), and avoids the operator getting embroiled in disputes concerning refusal to pay.
This solution does not solve the problem of theft, since a stolen telephone can be used.
There is a solution that analyzes the user's fingerprint in order to authorize the use of a mobile telephone.
However, this kind of solution prevents users sharing the mobile telephone; for example, the user cannot lend his mobile telephone to a family member or friend. Furthermore, additional equipment for analyzing the fingerprint is necessary and adds to the cost of the mobile telephone.
An object of the present invention is to remedy this situation.